高分辨率机载SAR外定标技术研究及精度分析

发布时间：2018-04-07 18:12

本文选题：天线方向　切入点：角反射器　出处：《西安科技大学》2015年硕士论文

【摘要】：辐射定标是通过定标器、热带雨林等已知雷达散射截面积的定标设备,获取定标参数,进而计算整幅图中每个单元的散射截面积。未经定标的SAR系统不仅系统稳定性差,测量重复率差,而且其图像无法精确地反映出来实际地物的散射特性[1]。这将直接影响到定量遥感工作的顺利完成。故对SAR系统进行定标势在必行。文章就SAR辐射定标技术问题展开研究,首先研究了基于均匀分布目标的天线方向图测试技术。主要在IDL环境下,采用平差方法剔除定标场地中非均匀地物,从而提高SAR图像目标的识别能力,并应用最小二乘方法拟合天线方向图。同时,采用Envi软件进行天线方向图测量。将两种方法结果与实测值进行比较,得出基于IDL均匀分布目标的测量方法更接近于实测值的结论。其次详细研究常用四类角反射器微波反射特性,并从制作工艺误差切入,详细的分析了不同加工误差对二面角角反射器及三角锥形角反射器影响。模拟结果表明:相比较其他影响因素,夹角及不平整度对角反射器雷达散射截面积影响程度较大。最后,详细的分析定标常数计算中的两种方法(积分法与峰值法)的优缺点并通过实验数据评价其定标精度。对上述的技术及相关结论,文章采用Terra-SAR数据及X波段机载SAR数据,进行实验验证与分析,得出以下几点结论:(1)在定标常数计算过程中,积分法较峰值法更为稳定。(2)在定标设备方面,三角形角反射器相比正方形角反射器、扇形角反射器定标结果更稳定。(3)机载SAR定标虽然受到飞行平台稳定性的影响,但在单次的实验中依然取得了较高稳定度的结果。
[Abstract]:Radiometric calibration is to obtain calibration parameters by calibrating the known radar cross section area such as scaler tropical rain forest and so on and then calculate the scattering cross section area of each unit in the whole picture.The uncalibrated SAR system not only has poor system stability and poor repetition rate, but also its image can not accurately reflect the scattering characteristics of real ground objects [1].This will directly affect the successful completion of quantitative remote sensing.Therefore, it is imperative to calibrate the SAR system.In this paper, the problem of SAR radiation calibration is studied. Firstly, the antenna pattern testing technique based on uniformly distributed targets is studied.In the environment of IDL, the adjustment method is adopted to eliminate the non-uniform ground objects in the calibrated site, so as to improve the recognition ability of the target in the SAR image, and the least square method is used to fit the antenna pattern.At the same time, Envi software is used to measure the antenna pattern.By comparing the results of the two methods with the measured values, it is concluded that the method based on the uniform distribution of IDL objects is closer to the measured values.Secondly, the microwave reflection characteristics of four kinds of common angular reflectors are studied in detail, and the effects of different machining errors on dihedral angle reflectors and triangular conical angle reflectors are analyzed in detail.The simulation results show that compared with other influencing factors, the angle and irregularity have a greater influence on the radar cross section area of the angular reflector.Finally, the advantages and disadvantages of the two methods (integration method and peak value method) in the calculation of calibration constants are analyzed in detail, and the calibration accuracy is evaluated by experimental data.For the above technology and related conclusions, this paper uses Terra-SAR data and X-band airborne SAR data to carry out experimental verification and analysis, and draws the following conclusions: 1) in the calculation of calibration constants,The integration method is more stable than the peak value method. (2) in terms of calibration equipment, the calibration results of triangular angular reflectors are more stable than those of square angular reflectors, although the airborne SAR calibration is affected by the stability of the flight platform.However, the results of high stability are still obtained in a single experiment.
【学位授予单位】：西安科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P237

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